(CBS) – Classes have been canceled Tuesday at St. Charles East High School, as many members of the student body recover from what is believed to be a norovirus outbreak.

Eight hundred students called in sick Monday, out of a student body of 2,500 students, says Jim Blaney, spokesperson for St. Charles School District 303. About 50 teachers also were gone.

Blaney says officials suspect it’s a norovirus outbreak.

“We cannot say definitely it is norovirus, but the symptoms of what many of the students are experiencing is consistent with the stomach virus,” he says. “Based on the symptoms that people are exhibiting, and based on what we know of that particular virus, that seems to be a likely culprit.”

The most common symptoms of norovirus include diarrhea, vomiting, nausea, and stomach pain. The virus is common this time of year, and can be spread easily in closed environments.

The illness typically goes away within 24 to 48 hours; good hygiene is essential to keeping the virus from spreading.

Blaney has been hearing from parents of feverish and achy kids.

“From what I’m hearing from the moms that I’ve talked to, it’s about 48 hours; and the people who get it feel really, really bad,” he said.

Norovirus is highly contagious. According to the U.S. Centers for Disease Control and Prevention, the amount of particles that would fit on the head of a single pin is enough to infect more than 1,000 people.

Gloved and masked workers have been working to kill the virus at the school; by using a bleach-based disinfectant solution to wipe down lockers, sinks, walls, and other areas.

But Blaney said those measures can’t stop the spread of the virus alone. That’s why all parents should expect a phone call from their child’s teacher on Tuesday.

“We’re contacting parents of all the students in their second-hour class to get an update on the health of as many students as we can, because it is from that information that we’ll make the decision on whether or not we’re having school on Wednesday,” he said.

Schools in the rest of District 303 will operate as normal Tuesday.

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